Is Zakat due on the entire amount borrowed and invested, or on the remaining amount after the loss?

Borrowing with interest is forbidden by Islamic law because it is usury (riba). As for investing money, it is permissible in principle, unless it leads to a forbidden act, such as trading in prohibited items or dealing with usury. The obligation of Zakat (definition) is conditioned upon the completion of a lunar year while possessing the minimum taxable amount (nisab (definition)).